Susan Lukjan's lawyers said the investigators that tried to find the origin and cause of that fire back in 2006 had heard the word arson before they even got started with their investigation. So that made them biased and unreliable.

The commonwealth said that's ridiculous.

"The methodology they used was unreliable, leading to unreliable conclusions," said Arson Research Project Director Paul Bieber.

"What we're trying to establish is that the experts for the prosecution did not follow the scientific method that they're supposed to do," said defense attorney Thomas Clay.

A jury convicted Lukjan of setting her St. Matthews business, Campbell's Gourmet Cottage, on fire to collect insurance money.

She served six months of a 12-year prison sentence before the state court of appeals overturned that conviction.

A second trial date has been set for September, and the commonwealth wants to use the same expert testimony, but the defense wants them gone for trial No. 2.

That's including the Alcohol, Tobacco, Firearms and Explosives, electricians and arson investigators.

"We're saying all experts presented by the prosecution, all their testimony and conclusions should be excluded because they failed to follow the scientific method required," said Clay.

"You know, bias is something that's thrown at every police officer, every expert, every person that's ever been called to testify. It's a common defense tactic, and they're welcome to argue it," said assistant commonwealth's attorney Leland Hulbert.

The commonwealth said its experts weren't biased, but instead used their years of experience to come to a reliable conclusion.

"I think that's what's in the record, and what's been shown is that our experts have over 100 years of experience," said Hulbert.

The argument between the prosecution and the defense didn't end Monday.

It will continue in early September, just a few weeks before her second trial is set to begin.